The present invention relates generally to articles of footwear, and in particular to a sole with adjustable sizing.
Methods for modifying widths of soles and midsoles for articles of footwear have been proposed. Chen (U.S. patent number 2005/0210710) teaches a footwear system having a sole adaptable to different dimensions of shoes. Chen teaches this system in order to facilitate the production of soles and reduce costs of preparing molds for fabricating soles by using a common mold for producing soles for shoes of different sizes. The Chen design includes a first sole and a second sole, where the second sole is intended to attach to the first sole and is configured to contact the ground. Chen does not teach a particular material for the second sole. The second sole of the Chen design comprises a front sole portion, a rear sole portion and a middle sole portion with each sole portion being separate (i.e. not connected). Each of the sole portions includes gaps or slots allowing the width of the sole portions to be modified more easily by compression or stretching. Each sole portion may then be attached to the corresponding portion (front, middle and rear) of the first sole. Because the sole portions may be compressed or stretched, they may be fit over different sizes of a first sole. In some cases, the gaps between each portion may be filled in by cutting or molding a foam or similar material to fill the gaps.
Although Chen does teach a second sole that may be modified to adjust to different widths, the Chen design uses sole elements with gaps, and requires an extra step of filling these gaps. Because Chen teaches a method where the sole portions are fixed in position according to their attachment with the first sole, this method may put strain on the sole portions as they are constantly being flexed or compressed, which may reduce some of properties of the sole portions such as strength or elasticity.
Beak (U.S. patent number 2006/0143950), teaches an injection molded Phylon midsole. Beak teaches a method for making a midsole and bonding the midsole to an outsole that provides a reduction in the number of defective midsoles produced due to normal variations in size associated with current Phylon molding techniques. In the Beak design, a horizontal through-groove and one or more cross through-grooves (the cross-through grooves being formed perpendicular to the horizontal through-groove) are formed in the midsole during molding. Once a midsole with these through-grooves has been produced, Beak teaches bonding the edge of the midsole to the edge of the outsole. Then, Beak teaches lightly pressing the central portion of the midsole against the central portion of the outsole.
Because the midsole has several through grooves, whenever the midsole is slightly larger than the outsole (due to variations associated with the molding technique) the grooves will contract, allowing the midsole to bond exactly with the midsole. Beak points out that such a design is preferred over current methods that would leave a lump or bulge in the center of the midsole when the midsole has a slightly larger size than the outsole due to the excess of material in the center of the midsole.
While Beak teaches a midsole with a size that may be slightly adjusted to the size of the corresponding outsole, Beak does not teach a method of adjusting the width of the midsole between various sizes, but instead teaches a method for returning a midsole with a small size deviation to the originally intended size, including a predetermined width. Since, in the Beak design, the final width of the midsole is set by the width of the outsole, there is really no freedom in choosing the final width of the midsole after the midsole has been manufactured.
Parkinson (U.S. Pat. No. 6,299,817) teaches a method for seamless construction of molded elastomer products. Parkinson teaches various latex-based liquid elastomer solutions having different material characteristics that can be applied to a heated mold in layers to form a product comprising multiple elastomer layers. As an example, Parkinson teaches a shoe sole that may be made using this process. Parkinson teaches the use of a heated mold that is a three dimensional replica of the finished shoe. The mold is then partially dipped in a liquid elastomer so that the first layer of the shoe sole is formed at the bottom of the mold. The process is repeated, with partial curing between each step, until multiple layers are formed on top of each other resulting in a finished shoe sole. Parkinson further teaches a method where the outsole may be formed using a single mold size, but stretched to accommodate various sizes of the article (presumably an upper or midsole). However, using the Parkinson design, an outsole that is adjusted to fit a larger midsole or upper must remain in a constantly stretched position.
Greene (U.S. Pat. No. 6,920,707) teaches a system for modifying properties of an article of footwear. In the Green design, various inserts are used in order to adjust one or more portions of the article of footwear. Various properties associated with the footwear such as width, length, arch and compliance of the soul may be modified by using various different inserts.
There is a need in the art for a method of adjusting sole widths that solves these problems.